Timing synchronization apparatus and method for multi-carrier modulation signals

ABSTRACT

Embodiments of the present invention provide a timing synchronization apparatus and method for multi-carrier modulation signals. Wherein the apparatus includes: a predicting unit configured to denoise delay of symbols received before a currently received symbol, and to predict delay of the currently received symbol or of a symbol received after the currently received symbol according to the denoised symbol delay and a sampling clock frequency offset; and a timing synchronization unit configured to perform timing synchronization according to a predicted value of the delay of the currently received symbol or of the symbol received after the currently received symbol. With the apparatus and method, a signal to noise ratio of multi-carrier modulation signals may be effectively improved, and an effect of a timing error on a communication system may be lowered, thereby improving performance of the communication system.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Chinese Application No.201310529306.1, filed Oct. 31, 2013, the disclosure of which isincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to the field of communications, and inparticular to a timing synchronization apparatus and method formulti-carrier modulation signals.

BACKGROUND

Currently, multi-carrier modulation is widely used in the field ofcommunications, which may be achieved by multiple technical means, suchas discrete multi-tone (DMT) and orthogonal frequency divisionmultiplexing (OFDM), etc. The multi-carrier modulation employs multiplesubcarrier signals, and divides a data stream into several sub-datastreams, so that the sub-data streams have much less transmission bitrates, and the data are used to modulate several subcarriers,respectively. Multi-carrier modulation signals are characterized in arelatively low subcarrier data transmission rate and a relatively longcode element period. At present, fast Fourier transform (FFT) is aneffective way of achieving multi-carrier modulation.

Multi-carrier modulation signals are relatively sensitive to a timingerror, which will bring inter-symbol interference (ISI) andinter-channel interference (ICI) to the multi-carrier modulationsignals, and degrade signal quality. Hence, timing synchronization needsto be performed to the multi-carrier modulation signals. Wherein, thetiming synchronization of the multi-carrier modulation signals includessymbol synchronization (or frame synchronization) and sampling clockrecovery. An object of the symbol synchronization is to find a correctFFT window, and an object of the sampling clock recovery is to align aclock of a receiver with a clock of a transmitter, including offset andjitter of clock frequencies.

It should be noted that the above description of the background art ismerely provided for clear and complete explanation of the presentinvention and for easy understanding by those skilled in the art. And itshould not be understood that the above technical solution is known tothose skilled in the art as it is described in the background art of thepresent invention.

SUMMARY

An object of embodiments of the present invention is to provide a timingsynchronization apparatus and method for multi-carrier modulationsignals, which are capable of effectively improving a signal to noiseratio of multi-carrier modulation signals, and lowering an effect of atiming error on a communication system, thereby improving performance ofthe communication system.

According to a first aspect of embodiments of the present invention,there is provided a timing synchronization apparatus for multi-carriermodulation signals, including: a predicting unit configured to denoisedelay of symbols received before a currently received symbol, and topredict delay of the currently received symbol or of a symbol receivedafter the currently received symbol according to the denoised symboldelay and a sampling clock frequency offset; and a timingsynchronization unit configured to perform timing synchronizationaccording to a predicted value of the delay of the currently receivedsymbol or of the symbol received after the currently received symbol.

According to a second aspect of embodiments of the present invention,there is provided a receiver, including the apparatus as describedaccording to the first aspect of embodiments of the present invention.

According to a third aspect of embodiments of the present invention,there is provided a timing synchronization method for multi-carriermodulation signals, including: denoising delay of symbols receivedbefore a currently received symbol, and predicting delay of thecurrently received symbol or of a symbol received after the currentlyreceived symbol according to the denoised symbol delay and a samplingclock frequency offset; and performing timing synchronization accordingto a predicted value of the delay of the currently received symbol or ofthe symbol received after the currently received symbol.

An advantage of embodiments of the present invention resides in that asignal to noise ratio of a multi-carrier modulation signal may beeffectively improved, and an effect of a timing error on a communicationsystem may be lowered, thereby improving performance of thecommunication system.

With reference to the following description and drawings, the particularembodiments of the present invention are disclosed in detail, and theprinciple of the present invention and the manners of use are indicated.It should be understood that the scope of the embodiments of the presentinvention is not limited thereto. The embodiments of the presentinvention contain many alternations, modifications and equivalentswithin the spirits and scope of the terms of the appended claims.

Features that are described and/or illustrated with respect to oneembodiment may be used in the same way or in a similar way in one ormore other embodiments and/or in combination with or instead of thefeatures of the other embodiments.

It should be emphasized that the term “includes/including” when used inthis specification is taken to specify the presence of stated features,integers, steps or components but does not preclude the presence oraddition of one or more other features, integers, steps, components orgroups thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the invention can be better understood with reference tothe following drawings. The components in the drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating principles of the present invention. To facilitateillustrating and describing some parts of the invention, correspondingportions of the drawings may be exaggerated or reduced in size. Elementsand features depicted in one drawing or embodiment of the invention maybe combined with elements and features depicted in one or moreadditional drawings or embodiments. Moreover, in the drawings, likereference numerals designate corresponding parts throughout the severalviews and may be used to designate like or similar parts in more thanone embodiment.

In the drawings:

FIG. 1 is a schematic diagram of a structure of a timing synchronizationapparatus for multi-carrier modulation signals of Embodiment 1 of thepresent invention;

FIG. 2 is a schematic diagram of a structure of a predicting unit ofEmbodiment 1 of the present invention;

FIG. 3 is a flowchart of a method for predicting by using average delayby the predicting unit of Embodiment 1 of the present invention;

FIG. 4 is a flowchart of a method for predicting by using infiniteimpulse response filtering by the predicting unit of Embodiment 1 of thepresent invention;

FIG. 5 is a schematic diagram of a structure of a timing synchronizationunit of Embodiment 1 of the present invention;

FIG. 6 is a schematic diagram of comparison of performance of using thetiming synchronization apparatus of Embodiment 1 of the presentinvention and not using the apparatus;

FIG. 7 is a schematic diagram of a structure of a receiver of Embodiment2 of the present invention;

FIG. 8 is a schematic diagram of a structure of hardware of the receiverof Embodiment 2 of the present invention; and

FIG. 9 is a flowchart of a timing synchronization method formulti-carrier modulation signals of Embodiment 3 of the presentinvention.

DETAILED DESCRIPTION

These and further aspects and features of the present invention will beapparent with reference to the following description and attacheddrawings. In the description and drawings, particular embodiments of theinvention have been disclosed in detail as being indicative of some ofthe ways in which the principles of the invention may be employed, butit is understood that the invention is not limited correspondingly inscope. Rather, the invention includes all changes, modifications andequivalents coming within the spirit and terms of the appended claims.

The timing synchronization apparatus and method for multi-carriermodulation signals of the embodiments of the present invention shall bedescribed below with reference to the accompanying drawings.

Embodiment 1

FIG. 1 is a schematic diagram of a structure of a timing synchronizationapparatus for multi-carrier modulation signals of Embodiment 1 of thepresent invention, which is arranged at a signal receiving side of acommunication system. As shown in FIG. 1, apparatus 100 includes: apredicting unit 101 and a timing synchronization unit 102; wherein,

predicting unit 101 is configured to denoise delay of symbols receivedbefore a currently received symbol, and to predict delay of thecurrently received symbol or of a symbol received after the currentlyreceived symbol according to the denoised symbol delay and a samplingclock frequency offset;

and timing synchronization unit 102 is configured to perform timingsynchronization according to a predicted value of the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol.

It can be seen from the above embodiment that by predicting delay of acurrently received symbol or of a symbol received after the currentlyreceived symbol according to denoised delay of previously receivedsymbols and performing timing synchronization based on the predictedsymbol delay, a signal to noise ratio of multi-carrier modulationsignals may be effectively improved, and an effect of a timing error ona communication system may be lowered, thereby improving performance ofthe communication system.

In this embodiment, any existing method may be used for obtaining thedelay of the symbols received before the currently received symbol andthe sampling clock frequency offset, and it is not limited inembodiments of the present invention. Following description is given byway of examples.

For example, the delay of the symbols received before the currentlyreceived symbol may be obtained by using a symbol delay detectionmethod; wherein, the symbol delay detection method is based on one ormore pilot subcarriers/subcarrier pairs;

when the detection is performed based on a pilot subcarrier, bymeasuring a phase shift φ_(k) of a k-th subcarrier, delay {circumflexover (τ)}_(sp) of a k-th symbol received before the currently receivedsymbol may be obtained by using formula (1) below:

$\begin{matrix}{{{\hat{\tau}}_{sp} = \frac{\phi_{k}}{2{\pi\left( {k - 1} \right)}\Delta\; f}};} & (1)\end{matrix}$

where, Δf denotes a subcarrier frequency interval, and φ_(k) denotes thephase shift of the k-th subcarrier, k being a positive integer;

when the detection is performed based on a pilot subcarrier pair, delay{circumflex over (τ)}_(pp) of the k-th symbol received before thecurrently received symbol may be obtained by using formula (2) below:

$\begin{matrix}{{{\hat{\tau}}_{pp} = \frac{\phi_{k_{1}} - \phi_{k_{2}}}{2{\pi\left( {k_{1} - k_{2}} \right)}\Delta\; f}};} & (2)\end{matrix}$

where, Δf denotes a subcarrier frequency interval, k₁ and k₂ denotesequence numbers of the subcarrier pair, and φ_(k) ₁ and φ_(k) ₂ denotephase shifts of corresponding subcarriers, k₁ and k₂ being positiveintegers.

If the detection is performed by using multiple pilot subcarriers orsubcarrier pairs, averaging of multiple pilot subcarriers/subcarrierpairs may be performed to the above estimated symbol delay.

According to the method above, the delay of several symbols receivedbefore the currently received symbol may be obtained; however,embodiments of the present invention is not limited thereto. Anyexisting method may be used for obtaining the sampling clock frequencyoffset according to the delay of the several symbols received before thecurrently received symbol, and it is not limited in embodiments of thepresent invention. Following description is given by way of examples.

For example, after the delay of the several previously received symbolsis obtained, the sampling clock frequency offset may be obtained byusing formula (3) below:

$\begin{matrix}{{{\Delta\; f_{s}} = {{- \frac{{\sum\limits_{k = {{N/2} + 1}}^{N}\;{\hat{\tau}}_{k}} - {\sum\limits_{k = 1}^{N/2}\;{\hat{\tau}}_{k}}}{\left( {N/2} \right)^{2}\left( {{2N_{SC}} + N_{CP}} \right)}}f_{s}^{2}}};} & (3)\end{matrix}$

where, {circumflex over (τ)}_(k) is delay of a k-th symbol receivedbefore the currently received symbol, N_(SC) is a number of subcarriers,N_(CP) is a number of cyclic prefixes, and f_(s) is the sampling clockfrequency offset.

FIG. 2 is a schematic diagram of a structure of predicting unit 101 ofthis embodiment; however, embodiments of the present invention are notlimited to such a structure. As shown in FIG. 2, predicting unit 101includes: a denoising unit 201 and a calculating unit 202; wherein,

denoising unit 201 is configured to denoise delay of the symbolsreceived before the currently received symbol;

and calculating unit 202 is configured to predict the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol according to the denoised symbol delay and the samplingclock frequency offset.

In this embodiment, any existing method may be used by denoising unit201 for denoising the delay of the symbols received before the currentlyreceived symbol, and it is not limited in embodiments of the presentinvention. Furthermore, the number of the denoised symbols receivedbefore the currently received symbol is not limited in embodiments ofthe present invention.

For example, the denoising unit may include an average value calculatoror an infinite impulse response filter; wherein,

when denoising unit 201 includes an average value filter, the averagevalue calculator is configured to calculate average delay of the symbolsreceived before the currently received symbol, and take the averagedelay as the denoised symbol delay; and wherein, the average delay maybe calculated by using formula (4) below:

$\begin{matrix}{{{\hat{\tau}}_{middle} = {\sum\limits_{k = 1}^{{2M} + 1}\;{c_{k}{\hat{\tau}}_{k}}}};} & (4)\end{matrix}$

where, {circumflex over (τ)}_(k) is delay of a k-th symbol receivedbefore the currently received symbol, c_(k) is a weighted coefficient, kbeing a positive integer; let K=2M+1, K being a positive integer.

Wherein, any existing method may be used for determining the weightedcoefficient, and it is not limited in embodiments of the presentinvention. For example, a weighted coefficient of an intermediate symbolin K symbols is relatively large, and a weighted coefficient of a symbolaway from the intermediate symbol is relatively small. If

${c_{k} = \frac{1}{{2M} + 1}},$the average delay is equally weighted averaging, that is, arithmeticalaveraging.

When denoising unit 201 includes an infinite impulse response (IIR)filter, the infinite impulse response filter is configured to performinfinite impulse response filtering to the delay of the symbols receivedbefore the currently received symbol, and take the infinite impulseresponse filtered delay as the denoised symbol delay. Wherein, afiltering function of the filter may be denoted by formula (5) below:

$\begin{matrix}{{{y(n)} = {{\frac{1}{p}{y\left( {n - 1} \right)}} + {x(n)}}};} & (5)\end{matrix}$

where, y(n) denotes an output signal filtered at an n-th time, y(n−1)denotes an output signal filtered at an (n−1)-th time, x(n) denotes aninput signal of the filter, p denotes a filtering coefficient, p>0, nbeing a positive integer, and n≦N, N denoting a number of the symbolsreceived before the currently received symbol.

In this embodiment, calculating unit 202 is configured to predict thedelay of the currently received symbol or of the symbol received afterthe currently received symbol according to the denoised symbol delay andthe sampling clock frequency offset; wherein, any existing method may beused as a predicting method, and it is not limited in the presentinvention. Following description is given by way of examples.

For example, calculating unit 202 may calculate the predicted value ofthe delay of the currently received symbol or of the symbol receivedafter the currently received symbol according to the above average delayand a delay offset caused by the sampling clock frequency offset, or theinfinite impulse response filtered delay and a delay offset caused bythe sampling clock frequency offset. Wherein, the predicted value may becalculated by using formula (6) below:{circumflex over (τ)}_(P,j)={circumflex over (τ)}_(middle)−(M+j)(2N_(SC) +N _(CP))Δf _(s) /f _(s) ²  (6)

where, j is a positive integer; when j=1, {circumflex over (τ)}_(P,j)denotes a predicted value of the delay of the currently received symbol;and when j=L and L is an integer greater than 1, {circumflex over(τ)}_(P,j) denotes a predicted value of delay of an L-th symbol afterthe currently received symbol; f_(s) denotes a sampling clock frequency,Δf_(s) denotes the sampling clock frequency offset, and−(M+j)(2N_(SC)+N_(CP))Δf_(s)/f_(s) ² denotes a delay offset caused bythe sampling clock frequency offset.

FIG. 3 is a flowchart of a method for predicting by using average delayby the predicting unit of this embodiment. As shown in FIG. 3, forexample, an averager is used as denoising unit 201 and an adder is usedas calculating unit 202; wherein, an existing method is used to obtaindelay of 2M+1 symbols received before the currently received symbol,averager 201 calculates average delay of the 2M+1 symbols, and adder 202adds up the average delay and a delay offset−(M+j)(2N_(SC)+N_(CP))Δf_(s)/f_(s) ² caused by the sampling clockfrequency offset, so as to obtain a predicted value of the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol; and when j=1, a predicted value of the delay of thecurrently received symbol is obtained, and when j=L and L is an integergreater than 1, a predicted value of the delay of the L-th symbol afterthe currently received symbol is obtained.

FIG. 4 is a flowchart of a method for predicting by using infiniteimpulse response filtering by the predicting unit of this embodiment. Asshown in FIG. 4, for example, an IIR filter is used as denoising unit201 and an adder is used as calculating unit 202; wherein, an existingmethod is used to obtain delay several symbols received before thecurrently received symbol, IIR filter 201 performs infinite impulseresponse filtering to the several symbols one by one, and adder 202 addsup the infinite impulse response filtered delay and a delay offset−(M+j)(2N_(SC)+N_(CP))Δf_(s)/f_(s) ² caused by the sampling clockfrequency offset, so as to obtain a predicted value of the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol; and when j=1, a predicted value of the delay of thecurrently received symbol is obtained, and when j=L and L is an integergreater than 1, a predicted value of the delay of the L-th symbol afterthe currently received symbol is obtained.

In this embodiment, timing synchronization unit 102 is configured toperform timing synchronization according to a predicted value of thedelay of the currently received symbol or of the symbol received afterthe currently received symbol. Wherein, any method in the prior art maybe used by the timing synchronization unit for performing the timingsynchronization according to the predicted value, and it is not limitedin embodiments of the present invention.

For example, let Δ_(j)+ε_(j)={circumflex over (τ)}_(P,j)f_(s); where, Δis an integral part, which is used in FFT window control in symbolsynchronization and clock recovery, and ε is a decimal part, which isused in correction of remaining symbol delay.

FIG. 5 is a schematic diagram of a structure of the timingsynchronization unit of this embodiment; however, embodiments of thepresent invention are not limited to such a structure. As shown in FIG.5, timing synchronization unit 102 includes: a symbol synchronizing unit501 and a remaining symbol delay correcting unit 502; wherein,

symbol synchronizing unit 501 is configured to perform FFT windowcontrol in symbol synchronization and clock recovery according to apredicted value of the delay of the currently received symbol or of thesymbol received after the currently received symbol;

and remaining symbol delay correcting unit 502 is configured to correctremaining symbol delay according to the predicted value of the delay ofthe currently received symbol or of the symbol received after thecurrently received symbol;

wherein predicting unit 101 obtains the delay of the symbols receivedbefore the currently received symbol before remaining symbol delaycorrecting unit 502 corrects the remaining symbol delay, and performsprediction based on the remaining symbol delay.

In this way, the correction of the remaining symbol delay is set as aforward structure, and loop delay in the prior art will not be produced,thereby further improving the performance of the communication system.

In this embodiment, the symbol synchronization and clock recovery of themulti-carrier modulation signals may be achieved based on the structureof the timing synchronization apparatus of this embodiment. In case ofperforming the symbol synchronization, a pilot subcarrier (such as asecond subcarrier) of a low frequency or a pair of relatively near pilotsubcarriers (such as a k-th subcarrier and a (k+1)-th subcarrier) may beselected in denoising and in predicting delay according to the delay ofthe previously received symbols; and in case of performing the clockrecovery, a pilot subcarrier (such as a N_(SC)/4-th subcarrier) of anintermediate frequency or a pair of pilot subcarriers (such as a secondsubcarrier and a N_(SC)/4-th subcarrier) adjacent to each other in anintermediate distance may be selected in denoising and in predictingdelay according to the delay of the previously received symbols;however, it is not limited in embodiments of the present invention.

FIG. 6 is a schematic diagram of comparison of performance of using thetiming synchronization apparatus of the embodiment of the presentinvention and not using the apparatus. As shown in FIG. 6, using thetiming synchronization apparatus of the embodiment may effectivelyimprove a signal to interference plus noise ratio (SINR) of amulti-carrier modulation signal.

It can be seen from the above embodiment that by predicting delay of acurrently received symbol or of a symbol received after the currentlyreceived symbol according to denoised delay of previously receivedsymbols and performing timing synchronization based on the predictedsymbol delay, a signal to noise ratio of multi-carrier modulationsignals may be effectively improved, and an effect of a timing error ona communication system may be lowered, thereby improving performance ofthe communication system.

And the correction of the remaining symbol delay is set as a forwardstructure, and loop delay in the prior art will not be produced, therebyfurther improving the performance of the communication system.

Embodiment 2

FIG. 7 is a schematic diagram of a structure of a receiver of Embodiment2 of the present invention. As shown in FIG. 7, receiver 700 includes atiming synchronization apparatus 701, which is the timingsynchronization apparatus according to Embodiment 1, and shall not bedescribed herein any further.

FIG. 8 is a schematic diagram of a structure of hardware of the receiverof Embodiment 2 of the present invention. As shown in FIG. 8, receiver800 includes a barrel shift register 801, an interpolator 802, a fastFourier transformer 803, a rotor 804, a numerical control oscillator805, a symbol delay detector 806, a clock frequency offset calculator807 and a predictor 808; wherein,

barrel shift register 801 is configured to perform symbolsynchronization according to a prediction result of predictor 808,interpolator 802 is configured to perform intra-symbol synchronizationaccording to output of numerical control oscillator 805, fast Fouriertransformer 803 is configured to perform FFT transform to signals, rotor804 is configured to correct remaining symbol delay according to theprediction result of predictor 808, symbol delay detector 806 isconfigured to obtain delay of symbols received before a currentlyreceived symbol, clock frequency offset calculator 807 is configured tocalculate a sampling clock frequency offset, and predictor 808 isconfigured to denoise the delay of the symbols received before thecurrently received symbol, and predict delay of the currently receivedsymbol or of a symbol received after the currently received symbolaccording to the denoised symbol delay and the sampling clock frequencyoffset.

In this embodiment, predictor 808 corresponds to the predicting unit inEmbodiment 1, barrel shift register 801 and rotor 804 correspondrespectively to symbol synchronizing unit 501 and remaining symbol delaycorrecting unit 502 in Embodiment 1, and methods in Embodiment 1 may beused by symbol delay detector 806 and clock frequency offset calculator807 for calculation, which shall not be described herein any further.Furthermore, structures of barrel shift register 801, interpolator 802,fast Fourier transformer 803, rotor 804, numerical control oscillator805, symbol delay detector 806 and clock frequency offset calculator 807are not defined in embodiments of the present invention.

In this embodiment, a method for obtaining delay of the symbols receivedbefore the currently received symbol, a method for denoising, a methodfor delay prediction and a method for timing synchronization accordingto a predicted value may be identical to those in Embodiment 1, whichshall not be described herein any further.

It can be seen from the above embodiment that by predicting delay of acurrently received symbol or of a symbol received after the currentlyreceived symbol according to denoised delay of previously receivedsymbols and performing timing synchronization based on the predictedsymbol delay, a signal to noise ratio of multi-carrier modulationsignals may be effectively improved, and an effect of a timing error ona communication system may be lowered, thereby improving performance ofthe communication system.

And the correction of the remaining symbol delay is set as a forwardstructure, and loop delay in the prior art will not be produced, therebyfurther improving the performance of the communication system.

Embodiment 3

FIG. 9 is a flowchart of a timing synchronization method formulti-carrier modulation signals of Embodiment 3 of the presentinvention, corresponding to the timing synchronization apparatus ofEmbodiment 1. As shown in FIG. 9, the method includes:

step 901: denoising delay of symbols received before a currentlyreceived symbol, and predicting delay of the currently received symbolor of a symbol received after the currently received symbol according tothe denoised symbol delay and a sampling clock frequency offset; and

step 902: performing timing synchronization according to a predictedvalue of the delay of the currently received symbol or of the symbolreceived after the currently received symbol.

In this embodiment, a method for obtaining delay of the symbols receivedbefore the currently received symbol, a method for denoising, a methodfor delay prediction and a method for timing synchronization accordingto a predicted value may be identical to those in Embodiment 1, whichshall not be described herein any further.

It can be seen from the above embodiment that by predicting delay of acurrently received symbol or of a symbol received after the currentlyreceived symbol according to denoised delay of previously receivedsymbols and performing timing synchronization based on the predictedsymbol delay, a signal to noise ratio of multi-carrier modulationsignals may be effectively improved, and an effect of a timing error ona communication system may be lowered, thereby improving performance ofthe communication system.

And the correction of the remaining symbol delay is set as a forwardstructure, and loop delay in the prior art will not be produced, therebyfurther improving the performance of the communication system.

The above apparatus and method of the present invention may beimplemented by hardware, or by hardware in combination with software.The present invention relates to such a computer-readable program thatwhen the program is executed by a logic device, the logic device isenabled to carry out the apparatus or components as described above, orto carry out the methods or steps as described above.

The present invention also relates to a storage medium for storing theabove program, such as a hard disk, a floppy disk, a CD, a DVD, and aflash memory, etc.

The present invention is described above with reference to particularembodiments. However, it should be understood by those skilled in theart that such a description is illustrative only, and not intended tolimit the protection scope of the present invention. Various variantsand modifications may be made by those skilled in the art according tothe spirits and principle of the present invention, and such variantsand modifications fall within the scope of the present invention.

Supplements

Supplement 1. A timing synchronization apparatus for multi-carriermodulation signals, comprising:

a predicting unit configured to denoise delay of symbols received beforea currently received symbol, and to predict delay of the currentlyreceived symbol or of a symbol received after the currently receivedsymbol according to the denoised symbol delay and a sampling clockfrequency offset; and

a timing synchronization unit configured to perform timingsynchronization according to a predicted value of the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol.

Supplement 2. The apparatus according to supplement 1, wherein thetiming synchronization unit comprises:

a remaining symbol delay correcting unit configured to correct remainingsymbol delay according to the predicted value of the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol;

wherein the predicting unit obtains the delay of the symbols receivedbefore the currently received symbol before the remaining symbol delaycorrecting unit corrects the remaining symbol delay.

Supplement 3. The apparatus according to supplement 1 or 2, wherein thepredicting unit comprises:

a denoising unit configured to denoise delay of the symbols receivedbefore the currently received symbol; and

a calculating unit configured to predict the delay of the currentlyreceived symbol or of the symbol received after the currently receivedsymbol according to the denoised symbol delay and the sampling clockfrequency offset;

wherein the denoising unit comprises:

an average value calculator configured to calculate average delay of thesymbols received before the currently received symbol; or

an infinite impulse response filter configured to perform infiniteimpulse response filtering to the delay of the symbols received beforethe currently received symbol.

Supplement 4. The apparatus according to supplement 3, wherein,

the calculating unit calculates the predicted value of the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol according to the average delay and a delay offset causedby the sampling clock frequency offset, or the infinite impulse responsefiltered delay and a delay offset caused by the sampling clock frequencyoffset.

Supplement 5. The apparatus according to supplement 4, wherein thecalculating unit calculates the predicted value of the delay of thecurrently received symbol or of the symbol received after the currentlyreceived symbol according to formula (1) below:{circumflex over (τ)}_(P,j)={circumflex over (τ)}_(middle)−(M+j)(2N_(SC) +N _(CP))Δf _(s) /f _(s) ²  (1)

where, M>0, and j is a positive integer; when j=1, {circumflex over(τ)}_(P,j) denotes the delay of the currently received symbol, and whenj>1, {circumflex over (τ)}_(P,j) denotes the delay of a j-th symbolreceived after the currently received symbol; {circumflex over(τ)}_(middle) denotes the average delay or the infinite impulse responsefiltered delay; N_(SC) denotes a number of subcarriers; N_(CP) denotes anumber of cyclic prefixes; f_(s) denotes a sampling clock frequency; andΔf_(s) denotes the sampling clock frequency offset.

Supplement 6. A receiver, comprising the apparatus as described in anyone of supplements 1-5.

Supplement 7. A timing synchronization method for multi-carriermodulation signals, comprising:

denoising delay of symbols received before a currently received symbol,and predicting delay of the currently received symbol or of a symbolreceived after the currently received symbol according to the denoisedsymbol delay and a sampling clock frequency offset; and

performing timing synchronization according to a predicted value of thedelay of the currently received symbol or of the symbol received afterthe currently received symbol.

Supplement 8. The method according to supplement 7, wherein theperforming timing synchronization according to a predicted value of thedelay of the currently received symbol or of the symbol received afterthe currently received symbol includes: correcting remaining symboldelay according to the predicted value of the delay of the currentlyreceived symbol or of the symbol received after the currently receivedsymbol;

wherein the delay of the symbols received before the currently receivedsymbol is obtained before correcting the remaining symbol delay.

Supplement 9. The method according to supplement 7 or 8, wherein thedenoising delay of symbols received before a currently received symbolincludes:

calculating average delay of symbols received before the currentlyreceived symbol; or

performing infinite impulse response filtering to the delay of thesymbols received before the currently received symbol.

Supplement 10. The method according to supplement 9, wherein,

the predicting delay of the currently received symbol or of a symbolreceived after the currently received symbol according to the denoisedsymbol delay and a sampling clock frequency offset includes: calculatingthe predicted value of the delay of the currently received symbol or ofthe symbol received after the currently received symbol according to theaverage delay and a delay offset caused by the sampling clock frequencyoffset, or the infinite impulse response filtered delays and a delayoffset caused by the sampling clock frequency offset.

Supplement 11. The method according to supplement 10, wherein thepredicted value of the delay of the currently received symbol or of thesymbol received after the currently received symbol is calculatedaccording to formula (1) below:{circumflex over (τ)}_(P,j)={circumflex over (τ)}_(middle)−(M+j)(2N_(SC) +N _(CP))Δf _(s) /f _(s) ²  (1)

where, M>0, and j is a positive integer; when j=1, {circumflex over(τ)}_(P,j) denotes the delay of the currently received symbol, and whenj>1, {circumflex over (τ)}_(P,j) denotes the delay of a j-th symbolreceived after the currently received symbol; {circumflex over(τ)}_(middle) denotes the average delay or the infinite impulse responsefiltered delay; N_(SC) denotes a number of subcarriers; N_(CP) denotes anumber of cyclic prefixes; f_(s) denotes a sampling clock frequency; andΔf_(s) denotes the sampling clock frequency offset.

The invention claimed is:
 1. A timing synchronization apparatus formulti-carrier modulation signals, comprising: a predicting unitconfigured to denoise delay of symbols received before a currentlyreceived symbol, and to predict a predicted delay of the one of thecurrently received symbol and a symbol received after the currentlyreceived symbol according to a denoised symbol delay and a samplingclock frequency offset; a timing synchronization unit configured toperform timing synchronization according to a predicted value of thepredicted delay of one of the currently received symbol and the symbolreceived after the currently received symbol; wherein the timingsynchronization unit comprises: a remaining symbol delay correcting unitconfigured to correct remaining symbol delay according to the one of thepredicted value of the predicted delay of the currently received symboland the symbol received after the currently received symbol; and whereinthe predicting unit obtains delay of the symbols received before thecurrently received symbol before the remaining symbol delay correctingunit corrects the remaining symbol delay.
 2. The apparatus according toclaim 1, wherein the predicting unit comprises: a denoising unitconfigured to denoise delay of the symbols received before the currentlyreceived symbol; and a calculating unit configured to predict thepredicted delay of the one of the currently received symbol and thesymbol received after the currently received symbol according to thedenoised symbol delay and the sampling clock frequency offset; whereinthe denoising unit comprises one of: an average value calculatorconfigured to calculate average delay of the symbols received before thecurrently received symbol; and an infinite impulse response filterconfigured to perform infinite impulse response filtering to the delayof the symbols received before the currently received symbol.
 3. Theapparatus according to claim 2, wherein, one of the calculating unitcalculates the predicted value of the predicted delay of the one of thecurrently received symbol and the symbol received after the currentlyreceived symbol according to the average delay and a delay offset causedby the sampling clock frequency offset, and the infinite impulseresponse filtered delay and a delay offset caused by the sampling clockfrequency offset.
 4. The apparatus according to claim 3, wherein thecalculating unit calculates the predicted value of the predicted delayof the one of the currently received symbol and of the symbol receivedafter the currently received symbol according to formula (1) below:{circumflex over (τ)}_(P,j)={circumflex over (τ)}_(middle)−(M+j)(2N_(SC) +N _(CP))Δf _(s) /f _(s) ²  (1) where, M>0, and j is a positiveinteger; when j=1, {circumflex over (τ)}_(P,j) denotes the delay of thecurrently received symbol, and when j>1, {circumflex over (τ)}_(P,j)denotes the delay of a j-th symbol received after the currently receivedsymbol; {circumflex over (τ)}_(middle) denotes one of the average delayand the infinite impulse response filtered delay; N_(SC) denotes anumber of subcarriers; N_(CP) denotes a number of cyclic prefixes; f_(s)denotes a sampling clock frequency; and Δf_(s) denotes the samplingclock frequency offset.
 5. A receiver, comprising the apparatus asclaimed in claim
 1. 6. A timing synchronization method for multi-carriermodulation signals, comprising: denoising delay of symbols receivedbefore a currently received symbol, and predicting delay of one of thecurrently received symbol and a symbol received after the currentlyreceived symbol according to a denoised symbol delay and a samplingclock frequency offset; performing timing synchronization according to apredicted value of predicted delay of one of the currently receivedsymbol and of the symbol received after the currently received symbol;wherein the performing timing synchronization according to a predictedvalue of the delay of the currently received symbol or of the symbolreceived after the currently received symbol comprises: correctingremaining symbol delay according to the predicted value of the one ofthe predicted delay of the currently received symbol and the symbolreceived after the currently received symbol; and wherein delay of thesymbols received before the currently received symbol is obtained beforecorrecting the remaining symbol delay.
 7. The method according to claim6, wherein the denoising delay of symbols received before a currentlyreceived symbol comprises one of: calculating average delay of symbolsreceived before the currently received symbol; and performing infiniteimpulse response filtering to the delay of the symbols received beforethe currently received symbol.
 8. The method according to claim 7,wherein, one of predicting delay of the one of the currently receivedsymbol and a symbol received after the currently received symbolaccording to the denoised symbol delay and a sampling clock frequencyoffset comprises: calculating the predicted value of the predicted delayof the one of the currently received symbol and the symbol receivedafter the currently received symbol according to the average delay and adelay offset caused by the sampling clock frequency offset, and theinfinite impulse response filtered delays and a delay offset caused bythe sampling clock frequency offset.